Locknuts of the prevailing torque type have previously been made by compressing opposite sides of the locknuts with plain rotatable forming wheels. As this is done, standard circular thread convolutions are forced radially inwardly to form lock thread convolutions. A machine for forming locknuts in this manner is disclosed in U.S. Pat. No. 2,464,728. Although locknuts made in this manner have been generally satisfactory in operation, under certain circumstances it is more desirable to provide accurate control of the axial extent of the lock thread convolutions.
Controlling of the axial extent of the lock thread convolutions has previously been done by forming nuts with special internally threaded collars which are deformed in the manner disclosed in U.S. Pat. Nos. 3,354,926 and 3,352,342. However for economic and other reasons, the forming of a locknut in the manner described in these patents has been somewhat unsatisfactory. This has resulted in a disclosure, in U.S. Pat. No. 3,457,979, of a locknut having punched indentations in side surfaces of the locknut.